"I listened to some of the music my oldest teenage daughter is listening to. And I was surprised at how different that music was from what I used to listen to." Natalia Komarova, an applied mathematician at U.C. Irvine.

"Since I'm interested in evolution in general, and a mathematical description of evolution, I thought studying the evolution of music would be a good idea."

Komarova and her team analyzed half a million songs released in the U.K. between 1985 and 2015 using online databases that describe songs' musical characteristics, like rhythm, mood and danceability. "For example here's a song that was high on the charts in 2014 that has high danceability: "Shake It Off" by Taylor Swift. <<CLIP: "Shake It Off">>

"Here's a 2014 song that has a low happiness index:" Stay with Me," by Sam Smith." <<CLIP: "Stay with Me">>

Overall, they found that songs had become less happy over the 30-year span; as well as more danceable, more relaxed—and more likely to have women behind the mic.

But the big hits bucked a number of those trends. "The behavior of successful songs looked almost like a separate species of songs. They have quantifiably different features, their own little trends."

Komarova's team was also able to predict a song's success, by judging only its musical qualities, about 75 percent of the time. "To me that's very positive. It means that music matters, for song success—it’s not just money."

Proving that, at least when it comes to their musical tastes… the kids are alright. <<CLIP: "The Kids Are Alright">>

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